1. Technical Field of the Invention
This invention relates to radio telecommunication networks and, more particularly, to a system and method of informing a radio telecommunications network of the operating capabilities, including the frequency band capability, of a mobile terminal operating therein.
2. Description of Related Art
North American cellular telecommunications networks traditionally operate in two frequency bands (A and B) in the 800-MHz hyperband. The most recent evolution in cellular telecommunications involves the adoption of six additional frequency bands (A-F) in the 1900-MHz hyperband for use in handling mobile and personal communications. The 1900-MHz hyperband is also known as the Personal Communication Services (PCS) hyperband. Frequency bands within the 800-MHz hyperband and the 1900-MHz hyperband are defined in EIA/TIA Standard IS-136, which is hereby incorporated by reference herein. Other standards which define cellular telephone operations in North America include EIA-627, EIA-553, and the intersystem signaling standard IS-41 which are also incorporated by reference herein.
Each of the frequency bands specified for the cellular and PCS hyperbands is allocated a plurality of voice or speech channels and at least one access or control channel. The control channel is used to control or supervise the operation of mobile stations by means of information transmitted to and received from the mobile stations. Such information may include, but is not limited to, incoming call signals, outgoing call signals, page signals, page response signals, location registration signals, voice channel assignments, maintenance instructions, short message service (SMS) messages, and cell selection or reselection instructions as mobile stations travel out of the radio coverage of one cell and into the radio coverage of another cell. The voice channel is used to carry subscriber telephonic communications as well as messages requesting mobile station assistance in making hand-off evaluations. The control and voice channels may operate in either an analog mode or a digital mode.
Mobile subscribers are now being offered new (optional and non-traditional) services in both the 800-MHz and 1900-MHz hyperbands, in addition to the traditional voice service on the 800-MHz bands. The next generation of digital mobile terminals, base stations, and Mobile Switching Centers (MSCs) must carry new functionalities or capabilities in order to realize these new non-traditional services. In addition, it is desirable to incorporate into the design of new mobile terminals, base stations, and MSCs a capability to optionally implement or not implement new functionalities or capabilities. Therefore, it is critical that new mobile terminals, base stations, and MSCs be informed of each other's ranges of supported capabilities, in order to properly allocate system resources and provide support for given services.
As an example, an existing cellular telephone network may simultaneously support radio telecommunications in multiple frequency hyperbands. A mobile switching center (MSC) within the network may control transmission and reception equipment at a base station to operate one cell in the 800-MHz hyperband and another cell in the 1900-MHz hyperband. Mobile terminals may also be capable of operating in either frequency hyperband. Thus it is critical that the MSC serving a particular mobile terminal be informed of the hyperband and frequency band capability of the mobile terminal, in order to successfully allocate a voice channel in one of the frequency bands supported by the mobile terminal. In addition, the whole range of mobile terminal operating capabilities may be required in order to properly allocate other network resouces necessary to provide requested services.
In existing cellular telephone networks, however, the operating capabilities, including the frequency band capability of a mobile terminal, are sent to the cellular network only in a few specified instances. IS-136 specifies several instances and methods for the mobile terminal to report its capabilities, but the methods do not always provide the information when it is required. There are cases when the information is needed by the network, but the mobile terminal is in a state in which the information cannot be requested. At specified registration cases, the mobile terminal can report its capabilities as information elements sent in system access messages, provided it is directed to do so by including an order in the overhead information sent to the mobile terminal by the network. According to IS-136, the mobile terminal only reports its capabilities at power-up registration, a new system registration, or a forced registration. These cases are limited so that bandwidth on the access channel is not misused, and primarily deal with a mobile terminal's first registration in a system.
There are two other existing methods for the telecommunications network to acquire the operating capabilities of the mobile terminal. The first method is to request the mobile terminal capabilities in a capability request message on the paging channel (PCC) while the mobile terminal is in state "DCCH Camping" or "Idle". Mobile terminal states during call setup are defined in IS-136. This method may be utilized if the network does not already have the mobile terminal capabilities while it has knowledge of the mobile terminal in a given service area. This situation could occur when the capabilities are not reported following a mobile terminal's access in a new service area. This method is best utilized if it is used immediately following a mobile terminal's first access, while the cell location of the mobile terminal is known (for example, following a successful mobile registration access on the DCCH). It should be noted that on the digital control channel (DCCH), a registration access should be the first access in a new service area. This method saves PCH resources by avoiding the sending of the capability request to several PCHs in a wide area (several cells) in an attempt to locate the mobile terminal.
The second method is to send a Capability Update Request message to the mobile terminal on the Fast Associated Control Channel (FACCH). This method is utilized when the mobile terminal has gained access to a digital traffic channel (DTC), while the network does not already have the required mobile terminal capabilities to continue with the processing of the call, and for handling call related events that may be required during the duration of the call. This method allows the retrieval of capabilities that are not provided in the capability report or are not available in any way from a call access for a specific service. In addition, a limited subset of the capabilities normally provided by the first method may be retrieved.
Before the mobile terminal receives a page, or before it makes an origination or any other type of access, the mobile terminal is in state "Idle". At that point, as noted above, it is possible to utilize the capability request on the PCH if the location of the mobile terminal is known in a particular service area. However, if the exact cell location of the mobile terminal is not known, a wide area paging must be performed to locate the subscriber. This process utilizes paging capacity and can only be avoided by using the first method described above immediately after the mobile terminal's registration access in a new service area.
A major disadvantage of these existing methods for the cellular network to acquire the operating capabilities of the mobile terminal is that there are instances when the cellular network needs to know the operating capabilities of a mobile terminal to properly allocate resources, but the network cannot obtain that information. In some of the mobile terminal call-setup states defined in IS-136, the mobile terminal cannot receive a capabillities request message and, therefore, cannot report its operating cabilities to the network. For example, when the mobile terminal has responded to a page and is in state "waiting for order", or after the mobile terminal makes an origination call and is in state "origination proceeding", the IS-136 standard does not allow the network to send the capability request message. In fact, IS-136 does not allow the capability request message to be sent in any of the defined mobile terminal states on the DCCH other than state "DCCH camping". Therefore, utilization of the first method above is limited because the capability request message cannot be sent to the mobile terminal while the terminal is in an intermediate traffic state after an initial access. The intermediate traffic states are registration proceeding, Shared Secret Data (SSD) update proceeding, origination proceeding, originated point-to-point teleservice proceeding, waiting for order, user group alerting, and terminated point-to-point teleservice proceeding.
In other words, the capability request message cannot be sent to the mobile terminal while the terminal is between any of the access states (registration proceeding, origination proceeding, waiting for order, etc.) and the idle state. It is critical that the network have the mobile terminal's capabilities before assigning resources such as a voice channel. Capabilities such as supported bands, DTC rate support, alternate/allowed voice coders for voice channel allocation, SOC or alternate system operator code (SOC) support, base station manufacture code (BSMC) support, protocol version, 800 MHz analog speech, etc. must be known by the network to properly allocate resources. If the network does not have this information, it makes arbitrary choices, which may be inefficient or incorrect.
In addition, mobile terminals capable of operating in either the 800-MHz hyperband or in the 1900-MHz hyperband may be tuned to digital control channels (DCCHs) in different hyperbands at different times. The serving MSC knows of the last known DCCH-hyperband used by the mobile terminal at system access. This information is normally used to page the mobile terminal on the DCCH in the appropriate hyperband. It may be useful in some cases to page the mobile terminal in all of the hyperbands which the mobile terminal supports, for instance, when the mobile terminal cannot be located using the last known hyperband. However, IS-136 does not allow for updating the DCCH-hyperband information for mobile terminals except at the specified registration cases. Therefore, cases may arise in which the network needs the hyperband capability to page the mobile terminal, but the information was not reported by the mobile terminal in the latest registration or other type of system access. If the network does not have this information, the call completion rate to subscribers may be reduced.
Although there are no known prior art teachings of a solution to the aforementioned deficiency and shortcoming such as that disclosed herein, U.S. Pat. No. 5,020,092 to Phillips et al. (Phillips) and U.S. Pat. No. 5,020,093 to Pireh (Pireh) discuss subject matter that bears some relation to matters discussed herein. Phillips and Pireh both disclose a dual-bandwidth cellular telephone that automatically switches its receiver bandwidth and control program for operation on a second cellular telephone system when service on a first system is not available. Phillips and Pireh do not teach or suggest a mechanism or method in a cellular telephone network for informing the network of the hyperband capability of mobile terminals attempting to access the network, or for updating the DCCH-hyperband information for mobile terminals.
Review of each of the foregoing references reveals no disclosure or suggestion of a system or method such as that described and claimed herein.
In order to overcome the disadvantage of existing solutions, it would be advantageous to have a cellular telephone network with a mechanism for informing the network of the mobile capabilities of a mobile terminal before the mobile terminal responds to a page or makes an origination call in the network. In addition, the network would have a mechanism for updating the DCCH-hyperband information for mobile terminals operating therein. The present invention provides such a network.